Home > Innovation, Invention, Research, Science, Technology > Laser beam used to cool down gas to a solid mass!

Laser beam used to cool down gas to a solid mass!

September 9, 2009 Leave a comment Go to comments

Laser beams are best known as weapons in science fiction and as heating and cutting tools in science fact. But a new study has flip-flopped conventional physics to show lasers in a whole new light.

Brian Handwerk of National Geographic News reports how Martin Weitz and Ulrich Vogl of the University of Bonn in Germany, in a new technique, used a laser to bring the temperature of dense rubidium gas far below the normal point at which the gas becomes a solid! Here’s how…

“Since a laser’s color is linked to its intensity, the new technique is based on using a red laser in which the frequency has been adjusted so that the beam affects the atoms only when they collide with each other.

Weitz and Vogl shone this laser beam into gaseous rubidium atoms in a high-pressure “atmosphere” of argon. But “during the very short period when a rubidium atom bangs into an argon atom, … [the rubidium] can absorb a photon” from the laser, NIST’s Porto explained.

The absorbed photon acts like a strong spring suddenly bridging the two atoms, and this weak link causes the atoms to slow down as they try to fly apart. But at some point the spring is stretched so far that the link breaks and the photon is released as scattered fluorescent light.

The extra energy required to slow the atoms gets carried away by the escaping photon, so the process ends up removing more energy than the laser puts in, cooling the gas.”


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